scholarly journals A novel method for objective identification of 3-D potential vorticity anomalies

2022 ◽  
Author(s):  
Christoph Fischer ◽  
Andreas H. Fink ◽  
Elmar Schömer ◽  
Roderick van der Linden ◽  
Michael Maier-Gerber ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Case Studies ◽  
Potential Vorticity ◽  
Three Dimensional ◽  
Simulation Models ◽  
Atmospheric Dynamics ◽  
Precipitation Event ◽  
Efficient Computation ◽  
Morphological Image Processing

Abstract. Potential vorticity (PV) analysis plays a central role in studying atmospheric dynamics and in particular in studying the life cycle of weather systems. The three-dimensional (3-D) structure and temporal evolution of the associated PV anomalies, however, are not yet fully understood. An automated technique to objectively identify 3-D PV anomalies can help to shed light on 3-D atmospheric dynamics in specific case studies, as well as facilitate statistical evaluations within climatological studies. Such a technique to identify PV anomalies fully in 3-D, however, does not yet exist. This study presents a novel algorithm for the objective identification of PV anomalies in gridded data, as commonly output by numerical simulation models. The algorithm is inspired by morphological image processing techniques and can be applied to both two-dimensional (2-D) and 3-D fields on vertically isentropic levels. The method maps input data to a horizontally stereographic projection and relies on an efficient computation of horizontal distances within the projected field. Candidates for PV anomaly features are filtered according to heuristic criteria, and feature description vectors are obtained for further analysis. The generated feature descriptions are well suited for subsequent case studies of 3-D atmospheric dynamics as represented by the underlying numerical simulation, or for generation of climatologies of feature characteristics. We evaluate our approach by comparison with an existing 2-D technique, and demonstrate the full 3-D perspective by means of a case study of an extreme precipitation event that was dynamically linked to a prominent subtropical PV anomaly. The case study demonstrates variations in the 3-D structure of the detected PV anomalies that would not have been captured by a 2-D method. We discuss further advantages of using a 3-D approach, including elimination of temporal inconsistencies in the detected features due to 3-D structural variation, and elimination of the need to manually select a specific isentropic level on which the anomalies are assumed to be best captured. The method is made available as open-source for straightforward use by the atmospheric community.

The Application of Grouting Technology in the Reinforcement Project of Montenegro Reservoir in Yunnan Province

2014 ◽  
Vol 1065-1069 ◽  
pp. 590-596
Author(s):  
Liang Zhang ◽  
Ju Rui Yang ◽  
Yu Zhuang Chen ◽  
Qiang Wang ◽  
Shi Jun Jiang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Case Studies ◽  
Yunnan Province ◽  
Construction Method ◽  
Saturation Line ◽  
Reservoir Engineering ◽  
Dam Foundation ◽  
Successful Case ◽  
Reservoir Project

Currently, dangerous reservoirs in Yunnan province are experience one serious common issue: leakage in dam body and dam foundation. To explore solutions for this issue, this study investigated the effects of the application grouting technology on dam seepage and reinforcement using case study of Montenegro reservoir project. Based on numerical simulation (STAB2005 Lizheng software), we can get results after having reinforcement, the dam saturation line was reduced after the reinforcement and the anti-seepage ability was improved significantly in both body and foundation of the dam. Furthermore, numerous successful case studies were reported using grouting technology. In conclusion, grouting technology is highly recommended as a construction method to solve leaking problems in reservoir engineering.

Potential Vorticity Diagnosis of the Severe Convective Regime. Part IV: Comparison with Modeling Simulations of the Moore Tornado Outbreak

2008 ◽  
Vol 136 (5) ◽  
pp. 1612-1629 ◽  
Author(s):  
David A. Gold ◽  
John W. Nielsen-Gammon
Keyword(s):  
Numerical Simulation ◽  
Conceptual Model ◽  
Case Studies ◽  
Potential Vorticity ◽  
Oklahoma City ◽  
Additional Insight ◽  
Convective Regime ◽  
Diagnostic Framework ◽  
Insight Into ◽  
Tornado Outbreak

Abstract A potential vorticity (PV) diagnostic framework is used to explore the sensitivity of the 3 May 1999 Oklahoma City tornado outbreak to the strength of a particular PV anomaly proximate to the geographical region experiencing the tornado outbreak. The results derived from the balanced PV diagnosis agree broadly with those obtained previously in a numerical simulation of the same event, while offering additional insight into the nature of the sensitivity. Similar to the findings of other cases, the balanced diagnosis demonstrates that intensifying (removing) the PV anomaly of interest increases (decreases) the balanced CAPE over the southwestern portion of the outbreak region, reduces (increases) the storm-relative helicity, and increases (reduces) ascent. The latter finding, coupled with the results of the modeling study, demonstrates that intensifying a PV anomaly proximate to an outbreak environment can increase the likelihood that more widespread and possibly less tornadic convection will ensue. The overall results of the balanced diagnosis complement those of other case studies, leading to the formulation of a conceptual model that broadly anticipates how the convective regime will respond to changes in intensity of upper-tropospheric weather features.

Development of Numerical Simulation Method for Melt Relocation Behavior in Nuclear Reactors: Validation of Applicability for Actual Core Support Structures

2016 ◽  
Author(s):  
Susumu Yamashita ◽  
Kazuyuki Tokushima ◽  
Masaki Kurata ◽  
Kazuyuki Takase ◽  
Hiroyuki Yoshida
Keyword(s):  
Numerical Simulation ◽  
High Temperature ◽  
Computer Aided Design ◽  
Nuclear Power ◽  
Radiation Heat Transfer ◽  
Three Dimensional ◽  
Simulation Models ◽  
Simulation Method ◽  
Transfer Model ◽  
Simulation Code

In order to precisely investigate molten core relocation behavior in the Fukushima Daiichi nuclear power station, we have developed the detailed and phenomenological numerical simulation code named JUPITER for predicting the molten core behavior including solidification and relocation based on the three-dimensional multiphase thermal-hydraulic simulation models. At the moment, multicomponent analysis method which can be treated any number of component as a fluid or solid body, Zr-water reaction model and simple radiation heat transfer model were implemented and showed that multicomponent melt flow and its solidification were confirmed in the simplified core structure system. However, the validation of the JUPITER using high temperature molten material has not been performed yet. In this paper, in order to evaluate the validity of the JUPITER, especially, for high temperature melt relocation experiment, we compared between numerical and experimental results for that system. As a result, qualitatively reasonable result was obtained. And also we performed melt relocation simulation on actual core structures designed by three dimensional CAD (Computer-Aided Design) and then we estimated phenomena which might be actually occurred in SAs.

Digital Reconstruction of Demolished Architectural Masterpieces, 3D Modeling, and Animation

2019 ◽  
pp. 206-241
Author(s):  
Roberta Spallone
Keyword(s):  
Case Studies ◽  
3D Modeling ◽  
Three Dimensional ◽  
Horse Racing ◽  
Three Dimensional Reconstruction ◽  
Digital Reconstruction ◽  
Methods And Techniques ◽  
Dimensional Reconstruction ◽  
Critical Approaches

This chapter reviews methods and techniques of digital reconstruction of disappeared architectural masterpieces. Through the overview of theoretical positions are explored heuristic values and communicative potentials of three-dimensional reconstruction, and prerogatives of animation in the interaction with three-dimensional data. Different critical approaches related to the architectures remained on paper are then brought to light. The examination of several case studies, also personally conducted, is extended to unbuilt architectures and minor architectures subject to demolition or transformation in order to highlight the different strategies used for the preservation of the memory of such heritage. Finally, the case study of Turin Horse-Racing Society Building by Carlo Mollino is extensively presented through the analysis of contemporary critical bibliography concerning the project, a description of archival sources and illustration of methods and techniques of the digital reconstruction.

Digital Reconstruction of Demolished Architectural Masterpieces, 3D Modeling, and Animation

2015 ◽  
pp. 476-509 ◽  
Author(s):  
Roberta Spallone
Keyword(s):  
Case Studies ◽  
3D Modeling ◽  
Three Dimensional ◽  
Horse Racing ◽  
Three Dimensional Reconstruction ◽  
Digital Reconstruction ◽  
Methods And Techniques ◽  
Dimensional Reconstruction ◽  
Critical Approaches

This chapter reviews methods and techniques of digital reconstruction of disappeared architectural masterpieces. Through the overview of theoretical positions are explored heuristic values and communicative potentials of three-dimensional reconstruction, and prerogatives of animation in the interaction with three-dimensional data. Different critical approaches related to the architectures remained on paper are then brought to light. The examination of several case studies, also personally conducted, is extended to unbuilt architectures and minor architectures subject to demolition or transformation in order to highlight the different strategies used for the preservation of the memory of such heritage. Finally, the case study of Turin Horse-Racing Society Building by Carlo Mollino is extensively presented through the analysis of contemporary critical bibliography concerning the project, a description of archival sources and illustration of methods and techniques of the digital reconstruction.

Numerical Simulation of Ultrasonic-Assisted Grinding Surfaces With Fast Fourier Transform

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Lin Li ◽  
Jinyuan Tang ◽  
Yuqin Wen ◽  
Caichao Zhu
Keyword(s):  
Numerical Simulation ◽  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Autocorrelation Function ◽  
Three Dimensional ◽  
Simulation Models ◽  
Research Focus ◽  
Ultrasonic Assisted Grinding ◽  
Ultrasonic Assisted ◽  
First Time

Abstract Numerical simulation of three-dimensional rough surfaces based on fast Fourier transform (FFT) is revisited. A more systematic approach, which is an extension of the current FFT-based simulation models, is proposed to approach surface reconstruction. Moreover, the simulation of the surfaces with machining signature by prescribing the parameters, take ultrasonic-assisted grinding as an example, has been taken as the research focus for the first time. The effectiveness is tested by three cases of simulation examples. Excepting the surface with exponential autocorrelation function, the simulation of surfaces with grinding machining marks is considered both by prescribing the theory autocorrelation function and by measuring a small area as a sample. The results show that the proposed method has great potential in engineering applications.

Computational Investigation of Full-Scale Tethered Underwater Kite

2018 ◽  
Author(s):  
Amirmahdi Ghasemi ◽  
David J. Olinger ◽  
Gretar Tryggvason
Keyword(s):  
Numerical Simulation ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Simulation Models ◽  
Slip Boundary Condition ◽  
Full Scale ◽  
Grid Resolution ◽  
Ocean Current ◽  
Computational Domain ◽  
Fixed Structure

In this paper, a numerical simulation of three-dimensional motion of tether undersea kites (TUSK) for power generation is studied. TUSK systems includes a rigid-winged kite, or glider, moving in an ocean current in which a tethered kite is connected by a flexible tether to a fixed structure. Kite hydrodynamic forces are transmitted through the tether to an electrical generator on the fixed structure. The numerical simulation models the flow field in a three-dimensional domain near the rigid undersea kite wing by solving the full Navier-Stokes equations. In order to resolve the boundary layer near the kite surface, adequate grid resolution is needed which increases the computational run time drastically especially in 3D simulations. Therefore, in this study a slip boundary condition is implemented at the kite interface to accurately predict the total drag, with lower grid resolution. In order to reduce the numerical run times, a moving computational domain method is also used. A PID controller is used to adjuste the kite pitch, roll and yaw angles during power (tether reel-out) and retraction (reel-in) phases. A baseline simulation study of a full-scale TUSK system is conducted in which the expected cross-current, figure-8 motions during a kite reel-out phase is captured. The effect of the tether drag on the kite motion and resulting power output is also investigated and compared with the results of the baseline simulation.

Development of Numerical Simulation Method for Relocation Behavior of Molten Debris in Nuclear Reactors: 1 — Preliminary Analysis of Relocation of Molten Debris to Lower Plenum

2013 ◽  
Author(s):  
Susumu Yamashita ◽  
Hiroyuki Yoshida ◽  
Kazuyuki Takase
Keyword(s):  
Numerical Simulation ◽  
Solid Phase ◽  
Initial Conditions ◽  
Three Dimensional ◽  
Simulation Models ◽  
Simulation Method ◽  
Melting Behavior ◽  
Hydraulic Simulation ◽  
Numerical Simulation Method ◽  
Two Phases

We developed the numerical simulation method for predicting the melting core behavior including solidification and relocation based on the three-dimensional multi-phase thermal-hydraulic simulation models. In this code, each of gas, liquid and solid phase are treated individually, and interface between two phases are simulated directly. In this paper, the developed code was applied to numerical simulations of the melting behavior of the simulated fuel assemblies and reactor structures. In the simulation, complicated structures in the BWR lower plenum was simply modeled. A decay heat in molten or solidified debris was also considered. Moreover, several different initial conditions were used to check performance of this code and to evaluate adequacy of the present numerical method. From the present numerical results, it was confirmed that relocation of molten debris in the BWR lower plenum can be simulated by the currently developed code including effects of melting and solidification of debris.

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